2.08 HIROSHI OHSHIMA 
Primary Pedicels.—A pair of the primary pedicels are 
first indicated by cireular pits formed on the ectoderm corre- 
sponding to the pedicel canals branching from the mid-ventral 
radial canal (PI. 9, fig. 22D, p; fig. 24 r, lp, rp). These I may 
eall pedal pits. The formation of the pedal pits a good deal 
resembles that of the stomodaeum, the rudiment of the 
pedicel being formed by the syncytium below the pit and arising 
from the bottom of the pit covered by the ectoderm. Finally 
it projects from the pit, the latter being soon flattened out. 
These changes strikingly resemble those found in the primary 
tentacles. ‘The pits are situated between the second and third 
ciliary bands and at an angle of about 40° on each side of the 
sagittal plane. Specimens are often found in which only one 
of the pair has just appeared. Of six cases of such specimens 
I observed all had only the left pedicel (PI. 9, figs. 21, 22, p). 
Out of seventeen cases where both the pedicels had appeared, 
eight cases showed that the left pedicel lies more or less anteriorly 
to the right one, while seven cases were the reverse, and in 
the remaining two cases the two lay on the same level. Thus 
we can find no constant feature as to the relative position of the 
two primary pedicels. 
According to Ludwig (22, pp. 185, 607), in C. planci 
the pedal pits appear in most cases near the end of the fourth 
day, and the pair of pedicel canals appear from the mid-ventral 
radial canal either at the end of that day or early on the next. 
Of the pair of pedal pits the right one always hes a httle anterior 
to the left one, and the same holds true in Phyllophorus 
urna as observed by the same author (24, p. 97). Newth 
(36, p. 637) found in the third-day larvae of C. saxicola 
and ©. normani that the posterior end of the mid-ventral 
radial canal formed a rhombic dilation representing the rudiments 
of pedicel canals. Here, he says, the left pedicel lies further forward 
than the right, just contrary to the feature seen in C. planci 
and Ph. urna. 
From Edwards’s observation (12, pp. 222-3) we learn that 
in H. floridana the first pedicel is unpaired and appears 
at the posterior end of the mid-ventral radial canal, It is said 
